The technology of the present disclosure relates to an image reading device and an image forming apparatus including the same.
In the related art, there has been known an image reading device that optically reads an image of a document placed on a contact glass and generates image data. In this type of image reading device, there is a case where the size of the document is detected. In this case, an illumination unit is used to irradiate liner illumination light long in a main scanning direction (a front and rear direction). In the illumination operation for detection of the document size, two light sources are respectively allowed to emit light at both end sides in the front and rear direction, so that light sufficient for detecting the size of a document sheet is irradiated.